The device disclosed in the present application forms part of a wrapper which is designed to wrap light paper such as on record jackets and game boards and also heavy stock on book covers and artist panels. Briefly, and in general, sheets of thin paper which may include any desired artwork, are individually fed through a gluing mechanism which applies and even coat of glue to one side of the sheet. After being glued, the sheet is transported to a spotting device which supports an individual sheet of heavy board over the glued wrap. Onee the spotting device has located the edges of the sheet or wrap (conventionally this is done by use of photocells which "read" the edges of the wrap) the board is spotted onto the glued wrap. The conveyor, supporting the combined wrap and board, transports the laminated sheets to a wrapper which includes a series of devices for sequentially folding the edges of the sheet around and onto the upper surface of the board.
A machine for sequentially wrapping or turning a thin sheet of paper around the edges of a flat board is made by Crathern Engineering Company, located at Maple Street, Contoocook, N.H., U.S.A. The wrapper manufactured by Crathern Engineering Company is sold in selected geographical areas of the world by the assignee of the present invention.
The covering sheet or wrap for a rectangular rigid board is cut so that corresponding dimensions are great enough to cover the edges and be adhesively attached to the opposite side of the board. Depending on the thickness of the board, it is usual to cut the wrap so that it extends about 1 centimeter (3/8 to 1/2 inch) inwardly from the edges of the board when it is adhesively attached thereto. The most difficult and the most important requirement is that the wrap be in firm contact with the corners of the board to thereby create a well defined board-wrap laminate. To fulfill such a requirement the corners of the wrap are cut at 45.degree.. When folded around the board edges and attached to the opposite side of the board, the intersection of the wrap edges define a mitered joint.
Achieving an acceptable corner appearance is the result of performing several things properly. Of primary importance is that the board be properly positioned on the glued wrap by the spotter. Failure to do so is usually apparent from the configuration of the corners which either fold in a way creating small wrap projections or a gap exists at the corner revealing an uncovered board edge.
Apparatus is presently incorporated in the wrapper for pressing the wrap along the opposed longitudinal edges of the board and, as the trailing or rear edge of the board passes the pressing device, the rear edge is also contacted in order to tuck the sheet against the rear edge. The presently used device has been found to be erratic in operation which is believed to be a result of its design which comprises a small diameter disc rotating about a vertical shaft. The disc mounts a series of circumferentially spaced pins which are parallel to the axis of rotation of the disc. When in engagement with the moving longitudinal edge of the laminated board two adjacent pins make contact therewith. As the trailing edge of the board passes by the pins, the disc is slightly indexed because when the trailing edge of the board passes the first pin, indexing of the disc occurs causing one of the pins to make pressure contact with the trailing edge of the board. Use of this device has been erratic due to the fact that the required stepwise rotation of the disc oftentimes does not occur.